There exist several different ways of analyzing a radio frequency (RF) signal.
One way of obtaining parameters of an RF signal is to detect the RF-signal with a measurement device, such as a digital oscilloscope or a network analyzer (e.g., (a scalar or vector network analyzer). For instance, the document US 2009/00921177 A1 describes a vector signal measuring system featuring wide bandwidth, large dynamic ranges and high accuracy using a network analyzer. This system incorporates at least two receiver channels per measurement port to provide absolute magnitude and absolute phase relationship. A wideband signal supplied at a specific measurement port of the system is sliced into several frequency sub-bands, wherein each frequency sub-band is analyzed separately and is compared to a parallel reference frequency band of the supplied signal. The measurement is repeated for all sub-bands. This measurement method, however, is very time-consuming and therefore not an efficient method for analyzing wideband signals.
Further, such measurement devices are heavy, space-consuming, complex in structure and highly cost-intensive, and thus are not flexible in use. The measurement devices also require a calibrated measurement probe to detect the RF signal and direct it into the measurement device. The probes, however, lead to measurement errors and influence the characteristics of the RF signal. Such errors may result from, for example, transmission and reflection losses of the probe due to parasitic electrical parameters, and moving of the probe and respective cables during the detection of the RF signal. Further, such measurement errors or inaccuracies cannot be calibrated or corrected.
Moreover, the accuracy of network analyzers or oscilloscopes is between 2 and 3 percent of the measurement signals magnitude. Due to their complex setup, such measurement devices suffer from intolerable ramp-up times. For example, due to the plurality of included modules the measurement devices have high measurement delays that result in long measurement times, especially for small powered input RF signals.
Another way of obtaining signal parameters of an RF signal is the use of specific signal sensors. For instance, the detection of an electrical power value of an RF signal can be achieved by the use of so called power detection sensors, such as sensors as described in the publication DE 2008 052 335 A1. Mainly two different types of power detection sensors currently exist, namely diode-based detecting sensors and thermal-based detecting sensors. Such detecting sensors are directly coupled to the RF signal source and provide an electrical power value at its output. Disadvantageously the use of such sensors is very limited to very specific signal magnitudes. For example, signals below 100 picowatts (−70 dBm) of average power are not properly detectable with such detectors. Especially sensors or detectors for sensing power signals with less than −20 dBm need noise compensation schemes due to their noise dependencies. Such noise compensations are normally realized by a reduction of measurement bandwidths at the output of the detector. An RF signal can therefore only be measured in a specific amount of measurement time. Therefore, a power detection of RF signals with high dynamic power ranges cannot be detected without significant measurement errors or significant measurement times.
What is needed, therefore, is a sensor that accurately analyzes low and high power wideband radio frequency signals in a low complexity and time efficient manner, for example RF signals with low power values (e.g., below 50 dBm). What is further needed is a sensor that is configurable for specific measurement tasks, and that provides signal parameters of the RF signal for efficient further signal analysis, for example, the sensor should provide signal parameters that can be handled easily in remote or subsequent devices without further calculations.